Amine catalysts are generally employed in the manufacture of polyurethane foam to catalyze the reaction between a polyisocyanate and a polyol to form the urethane linkages. Use of these somewhat volatile materials can cause such problems for workers as corneal edema or "blue haze", especially when improper ventilation is employed in foam processing. The problem of "blue haze" has also been experienced during amine manufacture. In addition, residual amines in foams have been associated with a yellow staining of workers' hands in some post-foaming processing operations, and there are also recurring concerns about residual amines contributing to odor in foams. Accordingly, it would be desirable to have amine catalysts in which the amines are substantially nonvolatile, and which still possess the required catalytic activity.
Another class of additives used in polyurethane foam manufacture is the acid-containing polyethers. Carboxylated polyethers have been prepared by grafting unsaturated carboxylic acids such as acrylic or methacrylic acid onto polymers and copolymers of ethylene oxide and propylene oxide. These carboxyl modified polyethers have found commercial use in metal working fluids, in urethane foam processing, and in commercial development of modified polyethers.
Modification of polyethers by free radical grafting was apparently first disclosed as such in U.S. Pat. No. 3,418,354 of M. L. Wheeler, assigned to Union Carbide. This patent was concerned with grafting silicones to polyolefins, but also broadly disclosed graft copolymers of acrylonitrile, styrene, methacrylates, acrylates, acrylic acid, methacrylic acid and vinyl esters on poly(alkylene oxides).
In 1985, U.S. Pat. No. 4,528,334 of Knopf et al. disclosed the process for grafting acrylic acid onto ethylene oxide/propylene oxide copolymers. This patent covered polyethers broadly, including polytetramethylene glycol (PTMEG). U.S. Pat. Nos. 4,686,240 and 4,701,474 of Bailey disclosed acid-grafted polyethers useful as urethane foam modifiers and controllers. U.S. Pat. No. 4,764,541 discusses another useful class of acid-containing polyethers which find utility in such applications.
The present application combines the general utility of certain amine catalysts with the low volatility (vapor pressure of less than 0.01 mm Hg at 25.degree. C.) of acid-grafted polyethers to yield novel catalysts for polyurethane foam manufacture, which do not suffer from the previously-discussed problems of volatile amine catalysts, and which may also offer additional advantages in foam processing.